1. Field of the Invention
The present invention relates to an injection molding machine, and particularly, to an injection molding machine for continuing operation in the event of a power outage.
2. Description of the Related Art
In an injection molding machine that drives an axis by a servo-motor, there is a need to continuously supply a power to a driving device of the servo-motor in order to drive the axis. For that reason, when a sudden power outage occurs and a power supply voltage becomes smaller than a voltage necessary for driving the servo-motor, the driving device of the servo-motor is stopped, and hence a problem arises in that a molding operation is stopped.
First, if the driving device of the servo-motor is stopped, a problem arises in that it takes a time until the molding operation is started again. Also, there is a problem in that a molding product, which is manufactured until the molding operation is stabilized after the molding operation is resumed, needs to be discarded as a defective product.
JP-A 2004-216829 discloses a technique of extending a voltage output maintaining time in the event of a sudden power outage by installing an energy maintaining circuit configured as an electric energy storage device in an electric circuit that supplies a control DC voltage to a driving device for driving a motor of a molding machine.
However, the technique disclosed in JP-A 2004-216829 has a concern that the cost of the molding machine may increase in that the molding machine additionally needs a device such as a converter circuit supplying a control DC power supply voltage to a plurality of drivers, a converter circuit supplying a control DC voltage to a molding machine control device, or an electric energy storage device.